The present invention relates generally to active antennas and methods of fabricating the same.
Phased-array antennas are capable of controlling the emission of electromagnetic information. A typical conventional phased-array antenna has an arrangement of radiating elements where the relative phase of radio frequency waves propagated through each radiating element can be controlled to steer the xe2x80x9cbeamxe2x80x9d of the antenna""s radiation pattern. Because of this beam-steering capability, phased-array antennas have been widely used in sophisticated radar systems.
Recently, phased-array antennas have drawn much attention and interest in the wireless communication area. Conventional wireless systems are limited because all the data channels in a cell or reception area must share the frequency bandwidth that is available. This limit can be greatly increased by using phased-array antennas, or by using schemes such as the BLAST(trademark) architecture from Lucent Technology, Inc.
Despite their superior capabilities, phased-array antenna systems have not been widely deployed for wireless communications because they often cost tens of millions of dollars. The hardware necessary to implement a phased-array antenna includes not only the antennas themselves. In one type of phased-array antenna, known as active arrays, each radiating element has associated electronics that include amplifiers and phase shifters. For transmission, amplifiers and phase shifters are needed for driving high frequency phased signals to each of the antenna elements. For reception, amplifiers and phase shifters are needed for phase-controlling and combining the received signal from each antenna element. The amplifiers, phase shifters and the driving circuitry are generally very complex and expensive.
An embodiment of the present invention is an active antenna that includes a substrate strip having an antenna element along one side of the strip, signal and power busses along another side, and one or more channel laid out across the strip of substrate material from the antenna element to the signal and power busses. The strip of substrate material may have a number of recessed regions and a number of shaped blocks disposed therein by a fluidic self-assembly process. The shaped blocks may include electronic devices such as micro-switches, CMOS control circuitry, and III-V semiconductor amplifiers. A two-dimensional phased-array antenna structure may be formed by stacking multiple substrate strips together.
Another embodiment of the present invention is a method of fabricating an active antenna using fluidic self-assembly techniques. In this embodiment, the method includes micro-machining shaped blocks containing electronic devices (e.g., micro-switches, CMOS control circuitry, and III-V semiconductor amplifiers, etc.), and forming recessed regions with matching profiles on a surface of a substrate. The surface is then treated to control surface forces, and the shaped blocks are dispensed on the surface in a liquid slurry. The shaped blocks self-align and fall into the matching recessing regions, forming a substantially planar assembly. Metalization and photolithography may then be applied to form signal and power busses, antenna elements, and waveguides on the substrate. Metalized lines for interconnecting the electronic devices to the waveguides, the signal busses, the power busses, and/or the antenna elements may also be formed. The method may further include stacking multiple substrates together to form a two dimensional phased-array antenna structure.